The present invention relates generally to a compact nozzle for laser welding. More specifically, the present invention relates to a laser welding nozzle that includes an air knife cross-jet to protect the laser optic, coaxially supplied process shield gas and active air cooling in a singular and compact nozzle.
Metal welding techniques have been researched, practiced and improved over a very long period of time. During this period a great many discoveries and advancements have been made in the manner in which a fusion weld is formed. In a conventional arc welding process, which is typical of the metal welding processes in use today, various impurities tend to contaminate the weld zone during the welding process and degrade the quality of the weld.
Various methods and systems have been used to minimize contamination in the fusion zone during these welding processes. For example, some of the more obvious steps include mechanical cleaning of the metals to be joined by such techniques as scrubbing, grit blasting and/or chemical cleaning. In addition, the workpiece to be joined may be preheated in order to drive off any adsorbed gases and moisture present. Similarly, through selective care and handling of the filler metal rods, the impurities which could otherwise enter into the weld zone from this source are minimized.
During the development of arc welding techniques, various gas shielding devices and methods have evolved that contribute significantly to the reduction of impurities in the weld zone. Additionally, cover gas or flux, as the case may be, can be maintained relatively contamination free subject to arc stability requirements. Another technique for minimizing the impurity content in the final weld is to use a filler rod having a suitable offsetting composition that complements the composition of the base metal in a manner which results in a final weld material composition that is within some preselected range.
Given the proximity of the laser focusing and delivery optics to the weld zone there is also a risk that welding plasma, slag and splatter can accumulate on the laser output optic. To protect against this blowing devices have been used. These devices typically have an elongated nozzle, which is directed at right angles to the laser beam and generate a gas flow passing through the laser beam. On the underside, the nozzle has an air feed, which opens in the vicinity of the nozzle opening and via which an incoming air flow can be fed to the gas flow at an acute angle. The housing of the laser head joins on the other side of the nozzle.
One of the major problems with these arrangements is that to accommodate the airflow required to effectively shield the optic and to provide the needed flow of process gas two separate feed systems and gas shrouds must be installed on or about that laser processing heads. This creates a system that is typically large and bulky in a manner that is not compatible with small movable laser processing head systems.
There is therefore a need for a system that provides a laser welding head that combines both a cross jet air knife to protect the laser processing optic as well as a gas shield delivery system into single compact apparatus. There is a further need for an apparatus that provides an air knife having airflow that is directed in a manner that provides active cooling of the laser while also directing flow in a manner that does not interfere with the process gas utilized in the shield delivery system.